MXA RACE TEST: THE REAL TEST OF THE 2025 SUZUKI RM-Z450
Yesterday at 02:00 PM
THE GEAR: Jersey: Hallman Roosted, Pants: Hallman Roosted, Helmet: Shoei VFX-Evo, Goggles: Scott Prospect, Boots: Sidi Crossair.
Q: FIRST AND FOREMOST, IS THE 2025 SUZUKI RM-Z450 BETTER THAN THE 2024 RM-Z450?
A: No! First introduced in 2018 and untouched in 2020, 2021, 2022, 2023 and 2024, it should come as no surprise that Suzuki didn’t change a thing on the RM-Z450 for 2025—not even the graphics.
However, as MXA’s “450 Shootout” deadline approached and the 2025 Suzuki RM-Z450 wasn’t forthcoming, we secured a virtually unused 2024 RM-Z450 and a week later got our 2025 Suzuki RM-Z450 . To be transparent, the 2025, 2024, 2023, 2022, 2021 and 2020 RM-Z450s are identical—using the 2024 RM-Z450 just allowed us allowed us to meet our production schedule without affecting the integrity of our test.
You might ask why our RM-Z450 had a Pro Circuit Ti-6 exhaust system on it. Were we cheating in the 450 Shootout? No, the aftermarket exhaust system comes stock on the “RM Army Edition.” The $1000 exhaust is used as a bonus for people who buy the RM-Z450 early in the selling season. It’s on our test bike because it came with it; however, we elected not to run the RM Army radiator shroud graphics.
Q: WHAT ARE THE CATEGORIES WHERE THE 2025 SUZUKI RM-Z450 MISSES OUT?
A: MXA’s job is to evaluate each machine thoroughly in order to analyze what it does well and what it does poorly. Here is a list of the RM-Z450’s no-no list.
(1) Weight. At 241 pounds before you put gas in the tank, the RM-Z450 is the heaviest bike on the track. It is 2 pounds lighter with the free Pro Circuit exhaust (making it weigh the same as a 2025 Kawasaki KX450). You might convince yourself that weight doesn’t matter, but added weight is not a plus when it comes to braking, acceleration, suspension or putting the RM-Z450 up on a bike stand.
(2) Horsepower. It’s slow. How slow? It makes 56.6 horsepower at a relatively low 9,000 rpm—(that is four horsepower less that the 2025 Husqvarna FC450). Sadly the RM-Z450 loses power at 10,000 rpm and 11,000 rpm and never gets to 12,000 rpm. But yes, Ken Roczen’s RM-Z450 is fast, but you can’t afford or even obtain the parts that are on his bike.
Take a good look at it! This is a kickstart lever and in 2025 it only exists on Suzuki motocross bikes.
Q: WHY DOESN’T SUZUKI JUST ADD AN ELECTRIC STARTER?
A: The Suzuki RM-Z450 is the only 450 motocross bike that doesn’t come stock with electric starting.
You might think that all the Suzuki engineers have to do is remove the kickstarter and its associated gears, and replace those parts with electric starter parts. We wish it were so easy. To do it right, and in motocross there is no other way, Suzuki would need all-new engine cases, complex gear combinations to allow the electric start to spin the engine at a very tightly prescribed rpm, and a wiring loom to integrate the contiguous electronics with the necessary battery.
And, you don’t need Sherlock Holmes to tell you that once Suzuki went that far, it would be a waste of R&D money not to redesign the valve train, cams, bore and stroke and layout of the engine with an eye towards losing weight. Oh yeah, did we forget to mention that all the required electric starter parts, including the battery, would add 5 pounds to the already-heavy RM-Z450.
What would it cost Suzuki to build an all-new RM-Z450 engine? Well over 10 million dollars.Perhaps Ken Roczen’s success helped sell more RM-Z450s, but since the bike has stayed frozen in time for the last five years, it’s more likely that racers dug into their garages and pulled out their old, mothballed RM-Z450s.
Q: HOW DOES THE 2025 SUZUKI RM-Z450 RUN ON THE TRACK?
A: For the average novice, vet or play rider, the existing RM-Z450’s power is located in the perfect spot on the rpm curve to get the job done; however, pros and high-rpm revvers will not like the RM-Z450 powerband because it gives up too much horsepower on top. After 9000 rpm, the RM-Z450 starts to lose the horsepower race to the class leaders. The RM-Z450 peaks at 54.87 horsepower at 8800 rpm, which is incredibly low in the powerband when compared to its competition. Need proof? By 11,000 rpm, the 2025 Suzuki RM-Z450 makes 7.5 horsepower less than a Yamaha, KTM or Husqvarna.
The 2025 RM-Z450 is not a lost cause, because if you short-shift it, you can keep it in the meat of its powerband. It has a very usable, pleasant and effective 450cc powerband. It is brisk off the bottom and strongest from 7000 to 8800 rpm. There is nothing wrong with a low-to-mid powerband on a 450cc motocross bike if you are able to maximize the good power and resist the urge to go searching for more where it doesn’t exist. After 9000 rpm, a Suzuki RM-Z450 engine makes noise, not horsepower.
For 2025 every Japanese brand has copied Suzuki’s “turn-at-all-costs” handling package, which could also be called the “head-shake-at-speed” handling package.
Q: WHAT ARE THE AREAS WHERE THE 2025 SUZUKI RM-Z450 SHINES?
A: Here is a quick list of where the Suzuki RM-Z450 shines.
(1) Price. Suzuki raised the price of the 2025 RM-Z450 from $9199 to $9299. It is still the cheapest 450cc motocross bike on the showroom floor, but jumping up from the $8000 price range into the $9000 range is bad marketing for what they are offering.
(2) Cornering. For decades the Suzuki was the best-turning bike on the track, so much so that all of its Japanese-built competition has embraced aggressive turn-in over high-speed stability. The Austrian bikes have managed to design in excellent turn-in without the liability of head-shake over rough ground.
(3) Powerband. Every MXA test rider liked the easy-to-use RM-Z450 powerband, not because of the quantity of horsepower, but because of the quality of the midrange powerband.
(4) Ergos. The bodywork, which was updated in 2018, is narrow. The bar bend is comfortable, and everything falls easily at hand.
(5) Tuneability. The 2025 RM-Z comes with three plug-in maps: Stock (white), Aggressive (white) and Mellow (grey). Additionally, Suzuki has a proprietary MX-Tuner 2.0 Apple and Android mapping tool.
(6) Color. The yellow plastic is a thing of beauty in motion. It looks clean even when it’s dirty.
Q: WHAT WOULD WE CHANGE IF WE WERE SO INCLINED?
A: Here is a breakdown of the simple mods that the 2025 RM-Z450 would benefit from—although your wallet would not.
(1) Gearing. We switched the stock 13/50 gearing for 13/51 sprockets. This allows us to get into third gear sooner and get more drive out of tight turns to make up for the horsepower deficit.
(2) High-pressure radiator cap. The stock 1.1 kg/cm2 RM-Z450 radiator cap allowed our RM-Z450’s coolant levels to drop during long motos. Twin Air and CV4 offer 1.8 kg/cm2 and 2.0 kg/cm2 radiator caps to raise the boiling point of the coolant.
(3) Heavy-duty clutch springs. Heavier springs improve clutch feel, increase bite on acceleration and increase the stock clutch plate life.
(4) Shock linkage. We have run the longer Pro Circuit shock linkage for the last couple of years. The longer link arms lower the rear of the Suzuki and stiffen the initial part of the shock stroke, which gave us more setup options.
(5) Suspension. After some bad years when they spec’ed the Showa SFF-TAC air fork, we had hoped for a big improvement when they switched back to Showa coil-spring forks, but that was not the case. You will probably end up sending these forks out for a re-valve.
(6) BFRC Shock. As for the rear shock, we hate the BFRC shock in consecutive bumps, on off-camber sections or when it starts oscillating on rebound. In truth, we have test riders who take the forks and shock off of the RM-Z250 and run them on the RM-Z450. You would think that the RM-Z250 suspension would be too soft, but it is just about right.
(7) More air. You can easily get an added burst of power by getting more air into the airbox. MXA cut holes in the side panels to help the engine breathe.
(8) Balance. This a six-year-old chassis, and our goal from day one was to get the rear end down and the front end up. The object was to kick the frame’s head angle out to slow down the steering input with the added benefit of lessening head-shake at speed. How did we achieve this?
We slid the forks down into the triple clamps. How far down? Flush with the top of the triple clamp. Plus, we added a longer Pro Circuit shock linkage to lower the rear of the Suzuki and stiffened the initial part of the shock stroke, which allowed us to have more options for compression and rebound settings, fork height and head angle.
Everybody raves about Honda and GasGas red, but yellow is the best color ever for a motocross bike.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Brakes. Suzuki has a 270mm front rotor. It’s powerful but grabby.
(2) Kickstart. The lack of an electric starter isn’t the end of the world for the Suzuki RM-Z450, but it is one of those things that a consumer believes adds value.
(3) BNG. In years when a manufacturer doesn’t make any mechanical updates, it would be wise to put more than zero effort into designing new graphics.
(4) Weight. It is the heaviest 450 on the track at 241 pounds (without gas in the tank); however, since the RM Army Edition exhaust system knocks 2 pounds off of the dry weight, it now weighs 239 pounds, which is exactly what a 2025 Kawasaki KX450 weighs.
The 2025 engine delivers usable low-to-mid power, but top-end power is lacking.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Cornering. The RM-Z450 is at its best on the entrance to turns. In its glory days, the Suzuki was the only bike that turned without effort—the competition has closed the gap.
(2) Power. The 2025 RM-Z450 has a well-placed powerband. That doesn’t mean that it has significant peak horsepower, just that the power it makes is very usable.
(3) Traction control. The 2025 RM-Z450 features a traction-control system that continually measures throttle opening, engine speed and gear position to adjust the ignition timing, and fuel-injector duration to stop wheelspin.
(4) Holeshot Assist. Suzuki’s Holeshot Assist Control (S-HAC) offers three mapping modes for different starting-line setups. We’d be happy with one launch-control button that didn’t require us to read the owner’s manual to operate it.
(5) Mapping. The GET-developed MX-Tuner 2.0 app allows you to remap the Suzuki RM-Z450 from your Apple or Android smartphone—once you jump through some hoops and get an external battery to power the electronics.
The 2025 Suzuki RM-Z450 shares the same 49mm Showa forks with the KX450 and CRF450, but MXA test riders prefer to put the stock RM-Z250 forks on the RM-Z450..
Q: WHAT WOULD WE LIKE TO CHANGE ON THE 2025 SUZUKI RM-Z450?
A: We don’t work for Suzuki, so far be it from us to tell them what they need to do to their bike. But, we do work for the racers who read our magazine, visit our website or watch our YouTube videos, and we owe it to them to provide accurate info about how the 2025 RM-Z450 could be improved.
(1) The Suzuki engineers should shave at least 10 pounds from the RM-Z450. It is too heavy—and so is the 2025 Kawasaki KX450.
(2) Adding electric start would be on our short list of updates that should be made to their next-generation RM-Z450 engine (if there is a next-generation engine coming down the pike).
(3) Get rid of the weird BFRC shock. It doesn’t do justice to the chassis.
(4) Suzuki has many very sharp engineers, and we have faith that, given free rein, they could design a better engine in their sleep.
(5) Build a clutch that maximizes power instead of slip.
(6) Listen to their customers and hire factory test riders who prioritize balance over partial fixes. We must assume that Suzuki doesn’t have any test riders, given that the RM-Z450 has been a product of Xerox engineering over the last six years.
(7) We know that Suzuki has the know-how to build a world-beating RM-Z450, but they don’t seem to have the will.
The Showa BFRC shock is a very creative idea. Instead of plunging the valve stack through oil in the shock body, it pumps it up to a valve stack in the piggyback. But, creativity has to work better to be worth the effort.
Q: WHAT IS THE BEST ADVICE THAT WE CAN GIVE ANY POTENTIAL SUZUKI BUYER?
A: If you buy a 2025 Suzuki RM-Z450, don’t spend any money on fancy aftermarket parts. Don’t hop-up the engine, and don’t throw money away on bling. Take all of your discretionary income and spend it on the suspension. Why? Because that is where the biggest improvement needs to be made.
The Pro Circuit Ti-6 exhaust system adds 2 horsepower and loses 2 pounds. Plus, it comes free, but only to early RM-Z450 buyers The offer expires on December 31, 2024.
Q: WHAT DO WE REALLY THINK?
A: It’s hard to look kindly on a motorcycle that is almost a vintage bike as it sits on the showroom floor, weighs a ton, isn’t very fast, is a disaster if you stall in a race, has poorly configured suspension components, and has the worst resale value of any bike on the used-bike market.
The Suzuki RM-Z450’s big claim to fame is that it is the cheapest raceable 450 motocross bike on the market—and why wouldn’t it be? After all, it’s a six-year-old machine. Its low-price claim is made hollow when you consider that a consumer could buy an all-new 2025 Honda CRF450 for only $400 more.
Last year we said that the 2024 Suzuki RM-Z450 was “the best bargain in motocross.” We don’t stand by that claim for 2025. The “best bargain in motocross” is the $9699 Honda CRF450.
The post MXA RACE TEST: THE REAL TEST OF THE 2025 SUZUKI RM-Z450 appeared first on Motocross Action Magazine.
